A federal judge has blocked the Trump administration from sending states lists of suspected noncitizen voters just hours before the midterms.
U.S. District Judge Tanya Chutkan ordered the Department of Justice and Department of Homeland Security to stop sharing the lists with state and local election officials amid concerns that eligible voters could be wrongly identified as noncitizens.
The ruling came as voters prepared to head to the polls in the midterms, with Republicans fighting to retain control of Congress.
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Chutkan, who was appointed by former President Barack Obama, granted a preliminary injunction in a lawsuit brought by the League of Women Voters, and other voting rights and privacy organizations.
The order prevented federal officials from distributing information identifying people as potential or confirmed noncitizen voters to those responsible for registering voters, processing ballots or certifying election results.
It also required the administration to submit a report within 24 hours confirming it had complied with the ruling and identifying a senior official responsible for ensuring it continued to do so.
However, the judge did not prevent federal authorities from responding to individual citizenship verification requests through the Systematic Alien Verification for Entitlements system or prosecuting violations of federal law.
The lawsuit, filed on October 15, challenged the administration's efforts to collect voter registration information from states and compare it with federal databases.
The groups argued that the initiative violated federal privacy protections and risked incorrectly identifying eligible American voters as noncitizens.
They also raised concerns that the administration was interfering with states' responsibility for running elections.
The Trump administration defended its efforts as part of enforcing federal election laws and preventing people who were not U.S. citizens from voting.
Noncitizens are already prohibited from voting in federal elections, although such voting is rare.
The dispute intensified in the weeks before the midterms as federal authorities tried to identify suspected noncitizens on state voter rolls.
In California, the administration claimed to have identified more than 20,000 registered voters who might not be U.S. citizens and sought to have their ballots separated from others until their citizenship could be verified.
State officials disputed the reliability of the information and warned that the demands could disrupt the election and prevent eligible Americans from having their votes counted.
A separate ruling Monday by U.S. District Judge James Boasberg blocked the administration from demanding that California election officials separate ballots or change their procedures based on the lists of suspected noncitizens.
The legal challenges formed part of a wider dispute over the federal government's role in elections, which are primarily administered by state and local authorities.
President Trump has repeatedly claimed that noncitizen voting poses a significant threat to U.S. elections, despite a lack of evidence that it occurs on a widespread scale.
His administration has argued that comparing voter registration records with federal immigration databases could help states identify people who are not legally entitled to vote.
Yet voting rights organizations warned that errors or outdated information in the databases could result in American citizens being incorrectly flagged.
Chutkan's order did not resolve the underlying lawsuit. Instead, it temporarily restricted the administration's activities while legal proceedings continued.
The court said a written memorandum opinion explaining the decision would follow.
Contact Newsweek editors for this story: Robert Greenall and Matthew Robinson